This invention relates to a magnetic reciprocating pump for pumping fluids, i.e. gases or liquids, with high pressures and at high temperatures, the pump having a piston freely movable in a tube of non-magnetic material and provided with recesses for the fluid to be pumped, a ball valve each being provided in the piston and in one end of the non-magnetic tube, and the drive force on the piston being transmitted by permanent ring magnets arranged outside of the non-magnetic tube, said ring magnets being reciprocated by a thrust rod driven by an electric motor.
Such a pump is known, cf. "The Review of Scientific Instruments", volume 41, No. 10, 1444-1446, October 1970. This pump can be employed only for temperatures of up to 200.degree. C., however, since the balls used there for the inlet and outlet valves are made of polytetrafluoroethylene (Teflon) which suffers from plastic deformations already at temperatures of about 200.degree. C. and moderately high pressures, the leak-proofness of the pump system thereby not being assured any more. Furthermore with this conventional pump system the passage for the thrust rod into the heated thermostat for driving the ring magnets is possible only with a high structural expense, the frictional losses occuring at the seal causing an extra load and a premature wear of the seal for the electrical drive system.